(A,B) Cross-section of the acinus-like Drosophila follicle; planar epithelial and luminal expansionary forces, as well as basement membrane-based resistance, are diagrammed. (C–E) As compared to the elongation of growing WT follicles (C), growth of follicles following ablation of epithelium (tjGAL4 GAL80ts>Diptheria toxin A chain [D]) is isotropic. Note the absence of epithelium-produced BM (inset). The aspect ratio is quantitated in (E). (F) Assessment of cortical tension in follicle epithelial cells using laser nanodissection (red) and Myo:GFP localization (blue). (G) Severing of A–P and circumferential cell junctions at anterior, center, and posterior positions results in comparable recoil velocities. Example A–P and circumferential cuts in G’ and G’’ are shown. (H) Junctional non-muscle MyoII (Myo:GFP) localization is equivalent along A–P and circumferential cell junctions. Representative example in H’. Scale bars: 25 µm in (A–C), 5 µm inset in (G’,H’).